Amphibians are Vertebrates

Amphibians are vertebrates, animals that have a spinal cord enclosed inside a backbone. Vertebrates have a long and amazing history on this earth. They have walked, slithered, hopped and swam on our planet for more than 500 million years, dating back to their appearance in the Cambrian Era. Vertebrates include the classes Mammalia, Aves (birds), Reptilia, Fish and the stars of our show, Amphibia. The first amphibians appeared on earth about 360 million years ago in the Devonian Period.  Many different kinds of amphibian have evolved (and also gone extinct) through the ages.  Today, three basic types exist – frogs and toads, salamanders and newts, and caecilians.

Compared to other modern vertebrates, amphibians have simple skeletons comprised of few bones. Of all the amphibians, salamanders have remained closest in body form to their ancient ancestors and are one of the oldest groups of terrestrial (land-living) vertebrates. Salamanders and newts have a somewhat flexible skeleton with a large amount of cartilage, while the frog or toad skeleton is more rigid and bony, more capable of withstanding the stress of jumping and landing. The frog skeleton also has a broad head, big eye sockets in the skull, a short spine and long hind leg bones. The worm-like caecilians lack legs entirely, their backbones may also possess more than 100 individual vertebrae, and they have a dense, compact and narrow skull that lacks eyes. A caecilian’s unique body shape is ideal for burrowing underground or swimming in ponds or streams.